Surgical microscopy systems are used, inter alia, in neurosurgical interventions in order, for example, to remove tissue afflicted by a tumor. Such a surgical microscopy system is distributed by the applicant under the trade name OPMI PENTERO 900. Here, the surgical microscopy system includes the actual surgical microscope with focusable imaging optics with preferably two eyepieces for stereo microscopy, corresponding lenses and objectives for magnified imaging of the actual operation field, wherein a focal point, that is, the distance between the focusable imaging optics and focal plane, at which a sharp optical image is obtained, is adjustable. Furthermore, provision can be made for illumination devices and/or data reflecting-in devices in order to superpose information directly into the field of view of the surgeon. Also, provision can be made for a second observation beam path for an assistant. Furthermore, the surgical microscopy system preferably comprises a camera in order to decouple, record and display an image of the operation field from an observation beam path. A display of a desired point in the operation field can be obtained with the aid of the focusable imaging optics. The actual surgical microscope is substantially freely movable in the operating theater by way of a stand with, in particular, a displaceable base unit. Here, the stand is embodied in such a way that the surgical microscope is freely movable relative to the base unit along all three direction axes (x, y, z) and likewise freely rotatable about three axes of rotation (α, β, γ) such that the surgical microscope can be aligned in any spatial direction. Hence, the surgical microscope can be brought into a desired position and alignment in order to be able to view the operation field from a desired spatial direction. The operation field is then subsequently imaged at a desired point by way of the focusable imaging optics, wherein the focal plane has a specific distance from the imaging optics. The surgical microscopy system is also equipped with a control device which controls all functions. By way of example, this is a computer which is operated with appropriate software.
A problem that often occurs in neurosurgical interventions is that, macroscopically, for example, tumor tissue cannot be distinguished unambiguously from healthy tissue. To this end, one or more tissue samples, in particular from the edge regions of the tumor, are then removed during the operation or the intervention via a biopsy, known per se, in order to directly examine a tissue sample in a pathological laboratory and classify the tissue as to whether or not it is pathological. Likewise, microscopic images can be recorded via a confocal laser endoscope (abbreviated CLE) and evaluated in the pathology department. Depending on the result from the pathology department, the surgeon can then make a decision either to take further samples or to remove the region of tissue which is suspected of having a tumor or leave healthy tissue untouched. Since some time elapses between the removal of the tissue and the availability of the pathological examination result, a surgeon can, in the meantime, examine other points. However, once the result is available, it is desirable to return with the surgical microscope to exactly the same position from where this sample was removed. The point of removal of a tissue sample should therefore be markable. To this end, for example, Erainlab has introduced a so-called “Curve System” in order to mark this position by way of an image-controlled guidance. Such systems enable an assignment of the current positions of surgical instruments, for example, for the purposes of the biopsy, or of a focal point of the surgical microscope in space to diagnosis data generated pre-surgery via stereotaxy.
Furthermore, what is known from WO 98/40025 is that a biopsy positioning sensor acquires the points at which a biopsy is taken in the three-dimensional space of the operation region and optically reproduces a reference point in a three-dimensional virtual image, which can be fed to the surgeon via a display. Hence, the surgeon can, as it were, return with his surgical microscope to the point where the biopsy was taken. Then, the virtual image can be superposed on the real image from the surgical microscope.